1. Field of the Invention
The present invention relates to a lighting device for vehicle use which conducts irradiation control of the lighting device in accordance with a road profile, vehicle operation and vehicle running condition.
2. Background
Conventionally, there is known a device by which an irradiating direction of a lighting device for a vehicle is changed in accordance with a steering angle of the vehicle. In this type device, the following problems may be encountered. As long as a steering member such as a steering wheel is not actually operated, the irradiating direction of the lighting device can not be changed. Therefore, it is impossible to adjust the irradiating direction of the lighting device into a direction in which the vehicle is advancing, just prior to a point in time at which the vehicle advances to a curved road.
In order to solve the above problems, there is proposed a device in which the navigation system (route guidance system) is used and the irradiating direction of the lighting device for vehicle use is changed before the advance of the vehicle to a curved road in accordance with the map information including profile data of the road and also in accordance with the positional information of the vehicle on a map provided in the vehicle. However, the above device is disadvantageous in that the irradiation control can not be completely conducted when the vehicle is on a road which is not included in the map information and also when the vehicle advances to a route not scheduled at an intersection. That is, when the navigation system can not be used or the vehicle advancing direction is changed at an intersection, priority is given to the driver's intention.
In order to solve the above problems, there is known a device in which priority is given to the irradiation control of the lighting device for vehicle use based on the operation of a direction indicator and the detection of a steering angle, over the irradiation control based on the map information.
It is possible to conduct irradiation control of the lighting device irrespective of the navigation system in the following manner. For example, a signal sent out from a direction indicator of the vehicle is discriminated, and the irradiating direction of the lighting device is changed in a direction of a track to which the signal is indicated. Alternatively, there is provided a detecting means for detecting a steering angle, and the irradiating direction of the lighting device is changed when a steering angle detected by the detecting means is larger than a predetermined value.
However, when the above method is adopted, the following problems may be encountered. Since priority is always given to the operation of the direction indicator of the vehicle and the result of detection of the steering wheel, when a driver mistakenly emits a signal of the direction indicator in an erroneous direction, the irradiating direction of the lighting device is changed in a direction at which the driver is not aiming. Also, when priority is excessively given to the detection of the detected steering angle, it become impossible to accomplish the primary object of changing the irradiating direction of the lighting device before the vehicle enters a curved road.